1. Field of the Invention
The present invention relates generally to drying systems and in particular to a radiant energy drying system for drying and curing fiber reinforced plastic products.
2. Description of the Related Art
A variety of manufacturing and processing procedures include steps wherein liquids are dried or cured. For example, coatings of various types, such as paint, sealants, printing inks, etc. are applied in liquid form and then dried or cured to relatively hard or durable finished conditions.
Various types of products are fabricated from molten materials which can be molded, cast, extruded and otherwise shaped in a variety of molds, dies, etc. to shape the finished products into appropriate configurations. The lengths of time required for such a product to harden or cure depend on several factors, including the nature of the liquid material, the presence of accelerators or retarders and ambiant conditions such as temperature and humidity.
Radiant energy can be applied to molded and liquid-formed products by, for example, exposure to sunlight and other radiant energy sources whereby drying and curing are hastened. Various types of dryers and lamps have been used for such purposes, such as the lamp assembly shown in the Keller et al. U.S. Pat. No. 4,000,407.
Boat hulls and decks are often fabricated with fiber reinforced plastic which is placed or laid up in molds. The freshly laid-up or "green" boat hulls and decks are sometimes exposed to direct sunlight to facilitate drying and curing the fiberglass resins. However, such sunlight curing procedures can be relatively time consuming, with drying times in the approximate range of four to eight hours. Also, relatively large products such as boats can occupy substantial amounts of exterior drying area, with attendant storage and handling problems. Still further, in many areas the availability of solar insolation tends to vary considerably with the seasons, cloud cover, azimuth angular orientations, etc.
Sunlight curing procedures also have a potential disadvantage of lacking control over the spectral ranges of the radiation, whereby the products being cured can be exposed to undesirable radiant energy in certain spectral ranges. For example, infrared radiation with wavelengths in the range of about seven hundred and fifty to one million nanometers and ultraviolet radiation in the "B" or "Beta" range of about one hundred and ninety to four hundred nanometers can be undesirable for certain drying and during processes. Therefore, for certain applications it would be desirable to provide a radiant energy drying system adapted for relatively large products and with capabilities of providing consistent output in desired spectral ranges with radiant energy output in undesirable spectral ranges filtered out.
The present invention addresses these problems with previous drying and curing procedures.